Method and system for inventory control

ABSTRACT

A method, article of manufacture, and apparatus for inventory control of items in a location are disclosed. In an embodiment, this comprises an identification tag associated with a transaction authorizing some items to be removed from the location, such as a purchase, an identification tag reader configured to read the identification tag and placed to cover a portion of the location, and a computer configured to process information including the identification tag read by the reader and take action in response, such as issuing an alert. The inventory control system may be further configured to detect when the identification tag is brought back into the location.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to co-pending U.S. patent application Ser.No. 10/986,833 for INVENTORY CONTROL and filed concurrently herewith,which is incorporated herein by reference for all purposes.

FIELD OF THE INVENTION

This invention relates generally to inventory control through use ofidentification tags such as radio frequency identification tags.

BACKGROUND

Inventory shrinkage is a significant issue for the retail industry,amounting to tens of billions of dollars in losses annually. Asignificant portion of these losses come from shoplifting, includingtheft of unpaid merchandise, fraudulent return of unpaid merchandise,and obtaining refunds for merchandise at a higher price than wasoriginally paid. These points of loss may involve receipts, whether realor counterfeit.

To combat inventory shrinkage, stores have employed methods such assurveillance, electronic article surveillance (EAS), marking receipts asused, and having a separate secure area for returning merchandise.Another approach involves the use of radio frequency identification(RFID) tags on every item, with a unique identifier for each tag so thatevery item can be tracked. However, this requires that every item havean RFID tag, which results in added expense and requires changes in themanufacturing and/or packaging processes. These methods may bepersonnel-intensive, expensive, and/or not completely effective inpreventing losses.

There is a need, therefore, for an improved method, article ofmanufacture, and apparatus for inventory control using identificationtags such as RFID tags.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings,wherein like reference numerals designate like structural elements, andin which:

FIG. 1 is a diagram illustrating components of an inventory controlsystem;

FIG. 2 is a flowchart illustrating an inventory control systemembodiment;

FIG. 3 is a flowchart illustrating an inventory control systemembodiment;

FIG. 4 is a flowchart illustrating an inventory control systemembodiment;

FIG. 5 is a flowchart illustrating an inventory control systemembodiment;

FIG. 6 is a flowchart illustrating the operation of the inventorycontrol system; and

FIG. 7 is a flowchart illustrating the operation of the inventorycontrol system in conjunction with a surveillance system.

DESCRIPTION OF THE INVENTION

A detailed description of one or more embodiments of the invention isprovided below along with accompanying figures that illustrate theprinciples of the invention. While the invention is described inconjunction with such embodiment(s), it should be understood that theinvention is not limited to any one embodiment. On the contrary, thescope of the invention is limited only by the claims and the inventionencompasses numerous alternatives, modifications, and equivalents. Forthe purpose of example, numerous specific details are set forth in thefollowing description in order to provide a thorough understanding ofthe present invention. These details are provided for the purpose ofexample, and the present invention may be practiced according to theclaims without some or all of these specific details. For the purpose ofclarity, technical material that is known in the technical fieldsrelated to the invention has not been described in detail so that thepresent invention is not unnecessarily obscured.

It should be appreciated that the present invention can be implementedin numerous ways, including as a process, an apparatus, a system, adevice, a method, or a computer readable medium such as a computerreadable storage medium or a computer network wherein programinstructions are sent over optical or electronic communication links. Ageneral purpose computer system such as an Intel-based processor runningMicrosoft Windows or Linux may be used, or a specialized appliance couldbe used. In this specification, these implementations, or any other formthat the invention may take, may be referred to as techniques. Ingeneral, the order of the steps of disclosed processes may be alteredwithin the scope of the invention.

An embodiment of the invention will be described with reference to aninventory control system in a retail environment, but it should beunderstood that the principles of the invention are not limited toinventory control in stores. Rather, they are applicable to anyenvironment in which it is desirable to control the provision ofservices and tangible objects. They may be applied to control ofinventory in a secured area, to ensure that inventory is not removedfrom the secured area unless authorized. Although the concepts hereinare described with respect to the use of radio frequency identification(RFID) tags, it should be understood that they are not limited to aninventory control system. Other identification tag devices capable ofautomatically uniquely identifying themselves (or the objects to whichthey are attached) may be used, such as barcodes, magnetic tags, radiofrequency transmitters/transponders, and ultrasonictransmitters/transponders. It is advantageous to use an automaticidentification device that does not require line of sight between thedevice and scanner, for ease of use and reliability, but line-of-sightdevices may be used in accordance with the full spirit and principles ofthe invention.

The principles of the invention may be used to secure the purchase ofgoods as well as services (such as restaurants, entertainment, etc.). Anembodiment of an inventory control system 10 is shown in FIG. 1. Itshould be understood that although particular numbers of each elementare used for illustrative purposes, any number may be used and theprinciples of the invention are not limited to any specific number ofsuch elements. Purchase receipts are commonly used in connection withthe provision of goods and services, and may be tagged with radiofrequency identification (RFID) tags 12. Alternatively, an RFID tag 12may itself be used as the receipt. At the time of the transaction, theRFID tag 12 is associated with the transaction, such as by scanning theRFID tag 12 with an RFID reader 28 and inputting its identification codeinto a computer 20 or RFID server 22 (which could be a computer aswell), which associates the identification code with the transaction. Bydoing so, the RFID 12 and the association it provides between thepurchased items and the bearer of the RFID tag/receipt may be used toprevent theft and fraud committed by exploiting the weaknesses of thecurrent security practices and systems through the use of real andcounterfeit purchase receipts. Typically, the items in inventory arelocated in a secured area in which it is desirable to keep those itemsuntil they are transferred (such as to a customer who has paid forthem).

RFID readers 28 in the form of radio frequency receivers configured toreceive signals from the RFID tags 12 may be disposed around the securedarea, and at access points via which ingress or egress may occur. TheRFID 12 may be an active transponder that contains a power source andtransmits its signal using that power source, or a passive transponderthat uses the energy of a transmitted signal from the RFID reader 28(which could be a transceiver) to transmit its own signal. The RFIDreader 28 may have a limited range and read the RFID tag 12 when the tagis in proximity to the reader. A video/audio server 24 and cameras 26may be used if a surveillance system is linked to the inventory controlsystem 10.

When the RFID reader 28 reads an identification code in the form of asignal from an RFID tag 12, the RFID reader 28 transmits informationabout the signal to a control center 20, which may be a computerconfigured to receive and track information about transactions, RFIDtags, time, date, location, etc. and cause alarms, notifications, andactions to be taken in response. A record may be made that an RFID tag12 was detected by a particular RFID reader 28 at a certain time andlocation. The computer 20 can store these and other events in a storagedevice. The location may be explicitly given by the RFID reader 28, orthe location may be determined by knowledge of the placement of thereader 28. Similarly, the timestamp may be sent by the RFID reader 28,or determined by the computer 20 upon reception of the information fromthe RFID reader 28. To reduce storage requirements, the computer 20 maybe configured to store only changes in state, or RFID server 22 may beconfigured to report only changes in state; i.e. instead of repeatedlyentering information that a tag is being read by an RFID reader 28, asingle report would be entered when the RFID reader 28 detects the RFIDtag 12, and another report would be entered when the RFID reader 28 nolonger detects the RFID tag 12.

A network 21 may be used to allow the control center to communicate withvarious RFID readers, alarms, and so on. The network 21 may be hardwiredor wireless, and the computer may comprise a network interface card topermit it to communicate over the network 21. This network 21 could be,for example, a local area network or wide area network. The computer 20also has a storage system to store data relating to RFID tags 12detected, transactions made, actions taken, and other information.Receipts may be provided with RFID tags 12 already attached orincorporated in them such as by embedding the RFID tag 12 betweenlayers, or a device for affixing an RFID tag 12 to a receipt. In thiscase, the RFID 12 could be incorporated into a “smart label” that has alayer of face stock and an adhesive layer, with the RFID tag 12 embeddedin between the layers. Attachment of the RFID tag 12 to the receipt mayalso be done manually.

The association of the RFID tagged receipt to the purchased itemscreates a means of preventing theft or fraud that can occur with RFIDsystems that do not associate the purchased items with the bearer of theRFID tag/receipt, as will be discussed herein.

In one common approach, a shoplifter may obtain a sales receipt bymaking an actual purchase, finding or stealing a real receipt, orcounterfeiting a receipt, and use the receipt in order to stealadditional merchandise or obtain cash. One method of exploitingweaknesses and gaps in the system (“exploit”) is for the shoplifter toproduce a counterfeit or cloned receipt, enter the store, pick up theitem(s) listed on the receipt, and take them to the customerservice/returns cashier in order to fraudulently obtain a refund.

In another method, the counterfeiter enters the store with thecounterfeit receipt, picks up the items listed on the receipt and leavesthe store with the goods. Even with a guard marking “used” receipts atthe door, the counterfeiter would be able to exit unchallenged becausethe counterfeit receipt is unmarked. Another method involves creating areceipt showing the purchase price of an item at the regular sellingprice. When the store runs a sale and discounts the price of the item,the counterfeiter returns to the store and claims a refund of thedifference in price between the “purchase price” and the then-discountedprice.

The shoplifter may also use a real receipt, obtained by either making alegitimate purchase or obtaining a legitimate receipt from the trash orbuying/stealing one from other customers. Using the real receipt, theshoplifter returns to the store, gathers the items listed on thereceipt, and walks out of the store without paying. This exploit ispossible in stores that do not mark the receipt as “used”. In storesthat do mark receipts as “used”, the shoplifter would not leave thestore but take the merchandise to the returns/customer service counterand fraudulently claim a refund.

The inventory control system 10 using RFID-tagged receipts as describedherein would know, even if the tagged receipt were discarded by acustomer, that the receipt/tag had been taken out of the building. Theinventory control system 10 could detect reentry of the receipt into thestore, and provide notification to store personnel. This would be thecase even if the shoplifter secretly brings the “real” tag/receipt intothe store. The system 10 would know that the original purchaser has leftthe facility and when the shoplifter takes some goods and presents themwith the receipt to the cashier for a refund, the system 10 will knowthat it did not detect reentry of the tag/receipt into the facility, andcould notify store personnel.

In case of a legitimate return, the customer will bring back the goodsand the receipt. If he returns with the tag/receipt the system 10 willinform store personnel who can then direct the customer and verify thecustomer's claims. The control center 20, if implemented in a computer,may have a screen to display messages to store personnel, an audiooutput to notify store personnel, or other means of communicatinginformation to users.

Surveillance may also be used to combat shoplifting. This approachrequires a live and/or recorded (e.g. video-taped) surveillance of thestore and its customers. The purpose is to provide a means ofsurveillance for security personnel, and to secure evidence againstshoplifters. This method is often inadequate for securing evidence dueto poor quality video and audio and suffers from at least two additionalshortcomings: 1) the method is costly since it requires trained andattentive personnel to monitor the activities of each customer, and 2)the method is highly inaccurate since the shoplifters are adept atavoiding detection and the monitoring personnel may frequently notnotice criminal activity. In some cases shoplifters may employ multiplepartners and attempt to create diversions away from the prime criminalact

Another approach involves marking receipts as used. This requires thestore to post security personnel at every exit of the store. In additionto other security duties, these personnel inspect every receipt of everycustomer leaving the premises and then mark each receipt with a markingdevice usually a pen or ink-marker. This method suffers from severalproblems: (1) The security personnel may not mark every receipt. Whenthe store is busy or the customer is not compliant, the securitypersonnel may not check and mark the receipt either through carelessnessor intimidation. Alternatively, the shoplifter may present a counterfeitreceipt for marking and leave the true receipt unmarked; (2) Even if areceipt is marked, that does not prevent the shoplifter from re-enteringthe store, gathering new merchandise from the store shelves, andreturning the un-purchased merchandise to the returns desk for afraudulent refund; (3) Shoplifters sometimes work with collaborators whoare employees of the targeted victim and work as security, customerservice, or cashier personnel. As collaborators, they work asaccomplices to the theft and subvert the security measures put in placeby their employer. As such, they may collaborate with the shoplifter andnot mark the receipt.

Separate secure areas may be used for returns, making use of physicalsecurity. Often, the customer service/returns cashiers are in the sameareas as the normal cashiers. This makes it easier for a shoplifter toreturn to the store with a “used” receipt and return un-purchased itemsfor a refund. The returns cashier may be located in such a way as tomake it difficult, if not impossible, for customers who have entered thestore for legitimate first-time purchases to enter the returns areaunnoticed. One method is to have the returns-customers enter thereturns-cashier area directly from the outside and not commingle returnstraffic with purchase traffic.

This method may be effective at reducing the marked receipt returnedgoods exploit because it makes it difficult, if not impossible, for ashoplifter to gather goods and take them to the returns-cashier withoutfirst exiting the store and going through the usual security systems.Its main failure is that it only minimizes false returns but doesnothing to prevent shoplifters from stealing goods (leaving the premiseswith unpaid goods). It is also ineffective in stopping shoplifters whouse counterfeit receipts from obtaining refunds for the differencebetween the “purchase price” and the then-discounted price.

Establishments that provide services are also vulnerable to theseexploits in similar manner. For example, a restaurant is vulnerable tocounterfeit receipts. A shoplifter can order and eat a meal and thenpresent to the cashier a fraudulent receipt that reflects a much lesscostly purchase.

The key enabling element in each of these exploits is the vulnerabilitycreated by the receipt itself. As described herein, some methods havebeen employed to combat the problem, but they each have sufficientweaknesses to make them vulnerable to exploit. One approach is to“serialize” each receipt with a serial number and/or barcode. Thismethod does not prevent false returns, and unless combined with physicalmarking or barcode scanning, does not prevent the shoplifter fromre-entering the store and leaving with a duplicate set of the itemsoriginally purchased. To prevent this exploit, the receipt's barcode orserial number would need to be scanned or checked upon exit with abarcode scanner which in most cases is not done, as it requires a personto inspect and scan receipts at each exit/entrance.

A solution to these exploits is the use of an RFID tag 12 on everyreceipt or making the RFID tag 12 itself the receipt. By tagging eachreceipt with an RFID tag 12 or by making the RFID tag 12 the receiptitself, the business has a means of authenticating every receipt andalso has the ability to collect complete purchase-lifecycle informationthat can be associated with every element of the purchase such as thepurchaser/customer, the items purchased, the location, date, time,cashier, exit/entry location, etc., and the receipt itself. This can bedone automatically, without requiring personnel to inspect and scanreceipts at each exit/entrance, which slows customers and may upsetthem. This information may be stored by the control system 20.

In an embodiment, every receipt issued is tagged with an RFID tag 12, orthe RFID tag 12 is the receipt itself. FIGS. 2 and 3 show embodiments ofan inventory control system implementation. Every entry and exit 40 tothe store may be equipped with an RFID tag reader 28 (or several), andmerchandise might not necessarily be tagged with RFID tags 12. It shouldbe understood that although this and other figures may depict aparticular number of RFID tag readers 28, any number may be useddepending on factors such as desired coverage. This would achieve thelowest cost deployment of RFID, because RFID tags 12 are applied only tothe receipts and not to the merchandise. This provides a means ofauthenticating the receipt and identifying when used receipts re-enterthe store, alerting the store personnel of the potential for theft.Further, in some deployments and proposed deployments of RFID for EAS(Electronic Article Surveillance), the RFID tag is deactivated or“killed” upon the item's purchase by the consumer, possibly due toprivacy concerns. In this case, the deactivated tag is no longer capableof identifying the article to which it is attached.

Upon purchase and at the time of payment, the cashier's station 30,which may be equipped with an RFID reader 28, registers which items arepaid for by reading the barcodes of the items or entering the item'sidentifier into the register 30. The item's identifier may indicate thetype of item and/or the specific instance of that item. Upon completionof payment, the cashier issues a purchase receipt which is tagged withan RFID tag 12. This information may be communicated to control center20 by the register 30 and the RFID reader 28, or the register 30 maytransmit the purchase information along with information from RFIDreader 28. The tagged purchase receipt is associated with every elementof the transaction such as the location or station ID of the cashier,the time and date, the individual items purchased and possibly theindividual article's serial numbers and/or barcodes, the form ofpayment, the specific payment instrument, and so on.

When the customer leaves the premises, an RFID reader 28 at the exitregisters the presence of the purchase receipt and records thetransaction as complete. The customer has taken the goods and left thepremises (i.e. taken “title” and full risk of loss). Several RFIDreaders 28 may be employed, for redundancy, coverage, and/or the abilityto detect the location and/or direction of movement of the RFID tag 12(i.e. placed so that it can be inferred from the order of detection bythe RFID readers 28 whether the RFID tag 12 is entering or leaving).Other methods may be used to determine the location and/or direction ofmovement, such as triangulation of signals from the RFID tag 12, lightbeams to detect the person carrying the tag, microwave sensors, etc.

The process is illustrated in FIG. 6. A transaction authorizing removalof items from the store (e.g. purchase) is performed in step 50. In step52, an RFID tag 12 is associated with the transaction (it may beattached to the receipt, be incorporated into the receipt, or be thereceipt itself). The computer 20 (or RFID server 22, which in turncommunicates with computer 20) receives information from RFID reader 28placed at exit 40 that the RFID tag 12 has been read, step 54. Thecomputer 20 determines whether the RFID tag 12 has been removed from thestore, step 56, such as by comparing timestamps of RFID reads reportedby adjacent RFID readers 28. RFID tags 12 are read and reported tocomputer 20, and if the system 10 determines that an RFID tag 12 hasbeen brought back into the store (i.e. it was already recorded as havingleft the store), step 58, an alert is issued in step 60. Suchinformation may be recorded in a storage device by computer 20.

Because the system 10 is fully automated, no personnel (trained orotherwise) are required to monitor any customers. This lowers theoperating cost for the operator of the inventory control system 10.Because the system 10 is able to gather all relevant purchasetransaction data and make the correct and necessary associations,attempts at fraud and theft are stopped.

People who re-enter the store with the tagged receipt, such as in aneffort to leave with duplicate goods, can be detected upon entry. Thesystem 10 would detect when tagged receipts enter the store, indicatinghigher risk. Upon entry of such a receipt the system 10 can notifysecurity personnel (using conventional computer output devices such as adisplay, for example), and the customer may be directed to theappropriate customer service desk (unless, of course, the personattempting to return is there to steal). If a person returns to thestore with the tagged receipt and without the goods in order to obtain anon-return, price adjustment refund (based on a price guarantee) thesystem 10 would detect the entry of the tagged receipt and alert thestore personnel. The inventory control system 10 could also be incommunication with an automated access control system for controllingingress and egress, such as one that employs computer-controlled gates.If combined with entry points which are physically different forpurchase and returns customers, the system 10 could detect and preventreturns customers from entering through the wrong entry point. FIG. 4shows an embodiment of the inventory control system 10 in aconfiguration utilizing separate purchase and returns/customer serviceareas, divided by a wall 42. The cashier's register 30 is segregatedfrom the returns register 31.

The inventory control system 10 could also be used to identify personsfor heightened surveillance. FIG. 5 illustrates an embodiment. Forexample, existing surveillance systems may incorporate a number of videocameras trained on particular locations within the store, a plurality ofdisplays to show the images produced by the video cameras, and speakersto reproduce sounds picked up by microphones on the cameras. Thesecameras may be configured to pan, zoom, and tilt automatically atregular intervals, or be remotely controlled by an operator who wishesto focus on a particular area. Most of the time, however, the imagesdisplayed are of little interest to security personnel, who mustcontinually watch the images from multiple cameras and attempt to spotsuspicious activity. The inventory control system 10 could notifysecurity personnel of heightened-risk persons entering the premises.This is shown in FIG. 7 as steps 70 and 72. The security personnel couldacquire a visual image of a heightened-risk person through a camera 26trained on the store entrance corresponding to the RFID scanner 28 thatsensed the RFID tag 12 carried by the heightened-risk person, andthereafter observe that person on the various cameras in the store.

By placing RFID readers 28 at various locations on the premises, theinventory control system 10 could assist in tracking the heightened-riskperson, such as by placing an identifying cursor on the video image(s)or automatically switching images to show the heightened-risk person.This may be done, for example, by creating a lookup table ofassociations between RFID readers 28 and cameras 26 that have them intheir field of view or can be moved to have them in their field of view.Step 74. The lookup table may comprise information about camera movementto cover a desired location, and the system 10 could automaticallyoperate a camera 26 to cover that desired location, with manual overridepossible through conventional means such as dials, joysticks, andswitches. The image from the selected camera(s) is displayed on themonitor(s), step 76. If the inventory control system 10 is equipped withthe ability to determine direction of movement of an RFID tag 12,another video display could be used to cover the predicted path of theheightened-risk person. As shown in step 78, video and/or audiorecording of the image(s) may be activated by the inventory controlsystem 10, which would track the person's movements, transactions, andactions. Timestamps and location information for the detected RFID tag12 can be recorded, either as metadata for the recordings or in datastorage separate from the recordings and used to index into therecordings. If the RFID tag 12 moves into range of another RFID reader28, step 80, another camera 26 may be selected to cover the newposition. With multiple displays, it is possible for the inventorycontrol system 10 to track multiple heightened-risk persons. This allowssecurity personnel to pay more attention to higher risk customers.

If every item available for purchase is tagged with an RFID tag 12,receipts may still be tagged with RFID tags 12 or RFID tags 12 providedas receipts. Every entry and exit 40 to the store may be equipped withone or more RFID tag readers 28. Upon purchase and at the time ofpayment, the cashier's station 30 may register which items are paid forby reading the RFID tags 12 of the items. Upon completion of payment,the cashier issues a purchase receipt that is also tagged with an RFIDtag 12. The tagged purchase receipt is associated with every element ofthe transaction such as the location or station ID of the cashier, thetime and date, the individual items purchased and possibly theirindividual serial numbers and/or RFID tags, the form of payment, thespecific payment instrument, and so on.

When the customer leaves the premises, the RFID reader 28 at the exit 40registers the presence of the purchase receipt as well as the items,shown as steps 54 and 62 in FIG. 6. In an embodiment, the inventorycontrol system 10 may resolve the purchase receipt RFID tag 12 to eachof the items transported by the customer through the exit 40, step 64.If there is an anomaly, such as a mismatch between the items transportedby the customer and the items associated with the purchase receipt'stransaction, an alarm or other notification takes place, step 66, andthe customer's packages may be inspected for unpaid merchandise. Also,if goods are detected by the RFID reader 28 by sensing their item RFIDtags, and there is no associated purchase receipt (with RFID tag 12),then an alarm may be generated and further inspection performed. This isshown as step 68 in FIG. 6.

This prevents shoplifters from stealing paid-for goods from thecashier's station 30 and exiting. In this exploit, the shoplifter is inline to pay for a purchase. As the shoplifter bags his/her goods s/hecovertly grabs goods that have been paid for by other customers in lineand puts them in his/her bag. The use of item-level serial number RFIDtagging of goods alone is insufficient to prevent this exploit, becausethe system only knows that the goods have been paid for and cannotassociate the goods with the person leaving the store. The inventorycontrol system 10 described herein can associate the goods with thetagged receipt and determine whether the tag/receipt leaving the storeis associated with the correct goods. If not, security personnel and/orsystems can be notified. In every case, unauthorized removal of goodsand/or services, whether accidental or intentional, is prevented.

Thus, the inventory control system 10 may be provided with the abilityto associate the person with the goods purchased. As the cost of RFIDtagging drops, its use may become more widespread at the item level, buteven with item level tagging there is no way to associate the goods withthe customer unless the customer is also tagged. The inventory controlsystem 10 described herein creates a per-transaction association betweenthe goods and the receipt. This is superior to customer-tagging becausea tagged customer can perform the unmarked receipt exploit unless allthe items also contain tags. The inventory control system 10 may combinereceipt-tagging with customer-tagging.

People who re-enter the store with the tagged receipt in an effort toleave with duplicate goods can be detected upon entry. The inventorycontrol system 10 would detect when tagged receipts enter the storewithout the associated goods that have been previously purchased. Uponentry of such a receipt the system 10 can notify security personnel, andthe customer may be directed to the appropriate customer service desk(unless, of course, the person attempting to return is there to steal).If a person returns to the store with the tagged receipt and without thegoods in order to obtain a non-return, price adjustment refund (based ona price guarantee) the system 10 would detect the entry of the taggedreceipt without the associated goods and alert the store personneland/or systems (such as automated systems for controlling ingress andegress). If combined with entry points which are physically differentfor purchase and returns customers, the system 10 can detect and preventreturns customers entering through the wrong entry point. As describedherein, any of these customers may be considered higher risk andselected for heightened observation by surveillance systems.

Although the methods and systems herein have been described with respectto an illustrative embodiment, it should be appreciated that the methodsand systems disclosed are independent of the precise architecture of theinventory control system. The principles are equally applicable toservice environments, such as restaurants, or any situation in which itis desirable to control movement of items from a particular area.

For the sake of clarity, the processes and methods herein have beenillustrated with a specific flow, but it should be understood that othersequences may be possible and that some may be performed in parallel,without departing from the spirit of the invention. Additionally, stepsmay be subdivided or combined. As disclosed herein, software written inaccordance with the present invention may be stored in some form ofcomputer-readable medium, such as memory or CD-ROM, or transmitted overa network, and executed by a processor.

All references cited herein are intended to be incorporated byreference. Although the present invention has been described above interms of specific embodiments, it is anticipated that alterations andmodifications to this invention will no doubt become apparent to thoseskilled in the art and may be practiced within the scope and equivalentsof the appended claims. More than one computer may be used, such as byusing multiple computers in a parallel or load-sharing arrangement ordistributing tasks across multiple computers such that, as a whole, theyperform the functions of the components identified herein; i.e. theytake the place of a single computer. Various functions described abovemay be performed by a single process or groups of processes, on a singlecomputer or distributed over several computers. Processes may invokeother processes to handle certain tasks. A single storage device may beused, or several may be used to take the place of a single storagedevice. The present embodiments are to be considered as illustrative andnot restrictive, and the invention is not to be limited to the detailsgiven herein. It is therefore intended that the disclosure and followingclaims be interpreted as covering all such alterations and modificationsas fall within the true spirit and scope of the invention.

1. A system for inventory control of items stored at a location,comprising: a passively machine readable identification tag associatedwith a transaction authorizing an item to be removed from the location;at least one identification tag reader configured to read theidentification tag and placed to cover at least a portion of thelocation; and a computer configured to process information including theidentification tag read by the reader and take an action in response tothe information; wherein the identification tag is not attached to theitem, and the information does not include data read from any passivelymachine readable tag attached to the item.
 2. The system as recited inclaim 1, wherein the identification tag is physically associated with areceipt for the transaction, and further comprising a device forattaching the identification tag to the receipt.
 3. The system asrecited in claim 1, wherein the information includes data associatingthe identification tag read with a portion of a database or index to adatabase where information regarding the associated event is stored. 4.The system as recited in claim 1, wherein the information furtherincludes location of the identification tag.
 5. The system as recited inclaim 4, wherein the information further includes a timestamp indicatingwhen the identification tag was read.
 6. The system as recited in claim4, wherein the information further includes a direction of movement ofthe identification tag.
 7. The system as recited in claim 6, furthercomprising placing readers in proximity to each other to detect theidentification tag, and wherein the computer is further configured todetermine the direction of movement of the identification tag bycomparing timestamps from the readers.
 8. The system as recited in claim1, wherein the identification tag includes a radio frequencyidentification tag.
 9. The system as recited in claim 8, wherein thereader is a radio frequency identification tag reader, placed to coveran access point to the location.
 10. The system as recited in claim 9,wherein the computer is configured to determine when the identificationtag has been removed from the location.
 11. The system as recited inclaim 10, wherein the computer is configured to determine when theidentification tag has been returned to the location.
 12. The system asrecited in claim 11, wherein the computer includes an output, and thecomputer is further configured to provide an alert to the output whenthe identification tag has been returned to the location.
 13. The systemas recited in claim 12, wherein the output includes a display.
 14. Thesystem as recited in claim 12, wherein the output includes an accesscontrol system configured to prevent passage when an alert is received.15. A method of controlling inventory of items stored at a location,comprising: performing a transaction authorizing an item to be removedfrom the location; providing, in connection with the transaction, areceipt including a passively machine readable identification tag;associating the identification tag with the transaction; anddetermining, using at least one identification tag reader placed tocover an egress from the location, when the identification tag has beenremoved from the location; wherein the item is not attached to a tagthat is passively machine readable.
 16. The method as recited in claim15, further comprising determining, using at least one reader placed tocover an ingress into the location, when the identification tag has beenbrought into the location.
 17. The method as recited in claim 16,further comprising issuing an alert after determining that theidentification tag has been brought into the location.
 18. A computerprogram product for inventory control of items stored at a locationhaving at least one identification tag reader placed to cover an accesspoint to the location, comprising a computer usable medium havingmachine readable code embodied therein for: associating a passivelymachine readable identification tag with a receipt for a transactionauthorizing an item to be removed from the location; and determiningwhen the identification tag has been removed from the location; whereinthe item is not attached to a tag that is passively machine readable.